The present invention relates to a deposition method and a focused ion beam system.
A focused ion beam system (FIB system) is a system which sputters the atoms that form the top surface of a specimen by scanning the surface of the specimen with a focused ion beam to etch an arbitrary minuscule area of the specimen. The focused ion beam system can also implement a deposition process that applies an ion beam to the specimen while blowing a compound gas on the area near the surface of the specimen to effect a chemical change in the area in which the ion beam is applied to deposit a film (see JP-A-3-289133 and JP-A-2007-134520, for example).
When the ion beam is applied to the area of the surface of the specimen which is filled with the compound gas, the ion beam collides with the compound gas molecules, and the gas molecules are decomposed. The decomposed gas molecules are adsorbed and deposited on the surface of the specimen. It is possible to deposit a film in an arbitrary area of the surface of the specimen by designating the target scanning range of the ion beam on the surface of the specimen in advance.
FIG. 14 is a view illustrating a deposition process (deposition operation) performed by a related-art focused ion beam system 101.
The focused ion beam system 101 opens a valve provided to a gas outlet of a gas gun 140, and inserts the gas gun 140 up to the upper portion near the surface of a specimen S that is supported by a specimen stage 120.
The focused ion beam system 101 focuses (just-focuses) the ion beam on the deposition target area of the surface of the specimen S using a focused ion beam optical system 110 and scans the deposition target area with the ion beam that is just-focused on the deposition target area. The gas molecules are thus decomposed and deposited on the surface of the specimen S in the area in which the surface of the specimen S is scanned with the ion beam.
After the focused ion beam system 101 has performed the deposition process for an arbitrary time, the focused ion beam system 101 stops scanning the surface of the specimen S with the ion beam. The focused ion beam system 101 then moves the gas gun 140 away from the surface of the specimen S, and closes the valve provided to the gas outlet of the gas gun 140.
A deposition film can be deposited by performing the above steps.
Since the focused ion beam system processes a minuscule area of the specimen, high processing accuracy is required, and the area near the top surface of the specimen is normally observed. A deposition film that is deposited using the focused ion beam system is used as a film that protects the top surface of the specimen during the FIB process (etching process).
Therefore, it is ideal to deposit a deposition film so as not to damage the surface of the specimen. However, since the deposition process utilizes an ion beam that is originally used for etching, the surface of the specimen may be scraped if a gas does not sufficiently fill the area near the surface of the specimen.
In the focused ion beam system, the specimen chamber is always maintained in a vacuum state during processing and deposition, and a gas is normally blown on the area near the surface of the specimen immediately before deposition, so that the gas locally fills the area near the surface of the specimen. Therefore, the surface of the specimen may be scraped by the ion beam in the initial stage of the deposition process due to lack of the gas. In such a case, a deposition film is deposited on the surface of the specimen that has been damaged from scraping by the ion beam.
In recent years, science and technology have remarkably developed, and various products have been reduced in size, integrated, and reduced in thickness. Therefore, it has been desired to further reduce damage during deposition of a deposition film.